Posted
by
Zonkon Sunday July 16, 2006 @04:22AM
from the i'd-like-a-dozen-no-a-hundred dept.

Anonymous 49'er writes "Nature is reporting that bacteria found in Australian gold mines are capable of extruding tiny invisible 'secondary grains' from soil and alluvial systems. From the article: "Potential applications -- from sensing the bacteria as a way to look for gold mines, to using them to help make industrially useful particles of gold -- may be some way off. But Southam is keen to exploit the bacteria's natural trick. 'I want to make a gold nugget one day,' he says. 'Gold nuggets grow in nature, so why shouldn't I be able to make one?'"

Judging by the number of responses so far I guess that asking about gold excreting bacteria is like asking about chocolate covered hubcaps. (that's a Larry Niven reference for those of you who are confused)

No, no. The question is -- what do you say to a chocolate-covered manhole cover?The short story of that title was very important in my life, because it quoted a very funny paragraph -- the Agnostic's Prayer -- from Roger Zelazny, who became one of my absolutely favorite writers (I am still angry at him for smoking and dying of lung cancer so prematurely).

Actually, I've been thinking of the story for its own sake a bit recently too, just because I argue with so many idiot creationists these days...

Surely we know where the gold mines are already - I mean, they tend to be biiiig things, or at least big holes in the ground. I wouldn't have though that looking for bacteria would make then any easier to spot.

Shouldn't the bacteria be used for finding gold _deposits_ instead?/ba-da ba-doom!/

There's no obvious mechanism by which gold should spontaneously form into nuggets in the wild; I don't really believe that gold particles in the soil magically find their way together by some mystical process of attraction.

Is it not more likely that these bacteria have been excreting gold as a matter of habit for hundreds of millions of years, and that gold nuggets are in fact the toilet pits of huge bacterial colonies from ages past? Perhaps the bacteria feed off sulphur or some other element that's mixed with the gold...

Yes, exactly!:-)I'm speculating that bacteria, in colonies, may be responsible for gold nuggets, at least in some cases. There are other cases of bacteria creating mineral concentrations (like stromatolites). Bacterial activity in hot rocks and hot springs is well known; gold is often found with other elements that some bacteria like, such as sulphur. Concentrations of gold don't seem to fit a natural process, I'd expect to see minerals dispersed within strata, not concentrated into pure blobs.

Most of the gold in the world is in archaean deposits or was transported from archaean sources by alluvial processes. In these deposits, the gold was dissolved from basalt rocks by superheated water, then precipitated out into cracks and fissures as the water got too cold to maintain the solution.
http://en.wikipedia.org/wiki/Ore_genesis#Gold [wikipedia.org]

The use of bacteria in mining is nothing new though. We've been using "bug leach" techniques in Australian mines for more than a decade. http://www.indmetlab.com.au/equipment/bio_metallur gy.php [indmetlab.com.au]
The main novelty of this species of bacteria is that it produces metallic gold instead of gold compounds. Given the relative ease of precipitating gold from solution, I'm not sure if it'll be enough of an advance to be worth using.

There is a large gold mine near where I live that uses bacteria to extract gold from the ore that is dug out of the mine. I'm not sure of the specifics, I'd have to ask my brother (he works at the mine), but basically, you feed the bacteria, and in return, they purify the ore. Gotta be better than chemical means such as arsenic and mercury.

Typically the type of gold mine that uses bug-leaching is a sulphide hosted deposit. The gold is encapsulated in sulphide mineral and is not available to be extracted. Fortunately, there are bacteria called Thiobacillus ferrooxidans who can dissolve and disintegrate sulphide matrices, thereby liberate the micron-sized gold grains.
The bugs don't actually leach the gold. After bug-leaching destroys the sulphides, you cyanide leach the heap to get the gold.
-AD

An old article from 2002...
Bacteria Point The Way To Gold Deposits
http://www.sciencedaily.com/releases/2002/05/02052 3075914.htm/ [sciencedaily.com]
Can bacteria help find gold? A pilot survey of 11 soil profiles across gold mining regions in the Peoples Republic of China indicates that elevated spore counts of Bacillus cereus, a common soil bacterium, were detected in areas adjacent to underlying gold deposits.....

From the insides of our intestines to animal carcasses to sewage plants to toxic waste sites, bacteria are crucial to cleaning things up. Surely this is yet another area where biotechnology will be hugely important in the 21st Century and beyond. In fact, if you're one of the IMO excessively laissez-faire "Oh, go ahead and pollute; technology will fix the problem later" types, you almost have to be betting on microorganisms as the solution. Almost everything else can be easily ruled out.

I was going to write a comment here about how such an incredibly useful bacteria can't possibly have evolved by itself, and must therefore be a dead giveaway that God exists, thus denying the need for faith (without which He is nothing), and so causing Him to vanish in a puff of logic.

But i'm too tired, so just pretend I wrote it and mod me funny appropriately.

Could this finally be the answer to Haber's problem of how to profitably extract gold from seawater. If so, I doubt anyone will let it happen for anywhere near the true cost of extraction (probably around a few dollars a troy ounce, once up & running). Which means a lot of biotech companies are going to be very very rich.Maybe I should patent the method of using a bioengineered bacterium to extract gold particles from seawater. Then I'd be richer than the biotech companies. Me thinks someone else go

There's a good chance these bacteria are already at work in the ocean. The problem with extracting gold from seawater is pumping all that water in and out of whatever it is you're using to extract it. For the bacteria method to work, every drop of gold-bearing water has to meet up with the bacteria colony long enough for the bacteria to extract the gold. Either you need a really big colony, or a really long time.

Since the price of gold has spiked lately, I've wondered about the cost of some of these al

back in late 70's/early 80's, I got my first degree in Microbio. so I paid attention to this. Back then, this was being explored (as well as doing it for leeching of other metals esp. copper, uranium, etc). The idea was to lower the energy needs, lower the environmental impact, and finally to be able to selectively go through garbage dumps and old leech fields. It actually makes great sense.

What bothers me about this is that we gave it up as oil prices were pushed down. We should have pushed it forward then.

Mineral deposits are basically geochemical anomalies where some substances is concentrated millions or billions of times normal background level.
Bacteria have been implicated in uranium, lead, zince, copper, petroleum and perhaps others.
A surprise has been the every deep drilling into the earth, up to eight miles deep,
has found teeming bacteria. These may have been when these rocks were at the surface, and/or bateria have gone deeper into the earth over billions of years.